“…While RCTs are costly and time‐consuming, real‐world data via prospective cohort studies are essential for investigating the epidemiology of the health status and potential safety issues and providing as basis for regulatory and health policy decision making. However, caution is needed here as such use of observational studies from routine practice data sources might hinder efforts needed to undertake prospective randomized controlled trials and may produce results discordant with RCTs 6,7 . We advocate that RCTs together with analyses of real‐world data (via improved epidemiological designs and methods to control for biases) are complementary and serve as the most robust study designs to investigate the efficacy, effectiveness, and safety of repeated plasmapheresis 8 .…”